Title: Statistical characterization of polychromatic absolute and differential squared visibilities obtained from AMBER/VLTI instrument Show Chinese title

Title: 来自AMBER/VLTI仪器的多色绝对和差分平方视宁度的统计特征

Abstract: In optical interferometry, the visibility squared modulus are generally assumed to follow a Gaussian distribution and to be independent of each other. A quantitative analysis of the relevance of such assumptions is important to help improving the exploitation of existing and upcoming multi-wavelength interferometric instruments. Analyze the statistical behaviour of both the absolute and the colour-differential squared visibilities: distribution laws, correlations and cross-correlations between different baselines. We use observations of stellar calibrators obtained with AMBER instrument on VLTI in different instrumental and observing configurations, from which we extract the frame-by-frame transfer function. Statistical hypotheses tests and diagnostics are then systematically applied. For both absolute and differential squared visibilities and under all instrumental and observing conditions, we find a better fit for the Student distribution than for the Gaussian, log-normal and Cauchy distributions. We find and analyze clear correlation effects caused by atmospheric perturbations. The differential squared visibilities allow to keep a larger fraction of data with respect to selected absolute squared visibilities and thus benefit from reduced temporal dispersion, while their distribution is more clearly characterized. The frame selection based on the criterion of a fixed SNR value might result in either a biased sample of frames or in a too severe selection. Show Chinese abstract

Abstract: 在光学干涉测量中，通常假设可见度平方模值服从高斯分布并且彼此独立。 对这种假设的相关性进行定量分析对于帮助改进现有和即将推出的多波长干涉仪的利用非常重要。 分析绝对平方可见度和颜色差分平方可见度的统计行为：分布规律、不同基线之间的相关性和交叉相关性。 我们使用通过VLTI上的AMBER仪器在不同仪器和观测配置下获得的恒星校准器观测数据，并从中提取逐帧传递函数。 然后系统地应用统计假设检验和诊断工具。 对于绝对平方可见度和差分平方可见度，在所有仪器和观测条件下，我们发现学生分布比高斯分布、对数正态分布和柯西分布更适合。 我们发现了由大气扰动引起的明显相关效应并进行了分析。 与选定的绝对平方可见度相比，差分平方可见度可以保留更大比例的数据，从而受益于减少的时间分散，同时其分布特征更加明确。 基于固定信噪比值的标准选择帧可能会导致样本偏向或选择过于严格。